Fifth wheel tractor-trailer combinations are common sights along most highways. Except for special load purposes, such trailers usually are rectangular in side cross-section with rear doors that open to allow loading from an elevated dock onto the flat floor of the trailer. The floor of the trailer rests on the fifth wheel attachment means and the rear wheels of the trailer so that the floor of the trailer which are positioned to maintain the floor relatively level during both loading and hauling. The flat trailer floor must be above its rear wheels. Therefore such conventional trailers have a relatively high center of gravity and a high aerodynamic load since their floor must be maintained a substantial distance above the pavement.
In some instances it is highly desirable to forward load a trailer, that is, shift its longitudinal center of gravity forward since this tends to make the loaded trailer more stable when being hauled. However, when a load is volume rather than weight limiting, there are no opportunities within a standard trailer to assure a forward center of gravity. It is also desirable that the load within the trailer never bear heavily on the rear door since the load can be lost if the rear door opens. Therefore, a solution to the aforementioned problems has been sought which does not abandon the utility of flat floor, level loading from a loading dock.
Aerodynamic advantages, efficiency, reduced drag and energy conservation are provided by the provision of an aerodynamic shroud over a frontal truss structure according to the invention which supports the trailer on a fifth-wheel assembly.